Migrated source files to new constants names.
Added devtools_protocol_constants.* generator.
Added sample generated files.

BUG=308512

Review URL: https://codereview.chromium.org/108363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239496 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239496